1) Field of the Invention
The invention is in the field of Microelectromechanical Systems (MEMS).
2) Description of Related Art
For the past several years, MEMS structures have been playing an increasingly important role in consumer products. For example, MEMS devices, such as sensors, detectors and mirrors, can be found in products ranging from air-bag triggers in vehicles to displays in the visual arts industry. As these technologies mature, the demands on precision and functionality of the MEMS structures have escalated. For example, optimal performance may depend on the ability to fine-tune the characteristics of various components of these MEMS structures. Furthermore, consistency requirements for the performance of MEMS devices (both intra-device and device-to-device) often dictate that the processes used to fabricate such MEMS devices need to be extremely sophisticated.
MEMS resonators are also becoming more prevalent. For example, motion sensors may be fabricated from a resonant accelerometer. FIG. 1 illustrates a cross-sectional view representing a MEMS structure having a resonant accelerometer, in accordance with the prior art.
Referring to FIG. 1, a MEMS structure 100 comprises a resonating member 102 coupled to an anchor 104 and a mass 106. In response to a motion, i.e. a positional displacement of MEMS structure 100, mass 106 oscillates in the direction of arrow 108. The oscillation of mass 106 alters the rigidity of resonating member 102, thus modifying the resonant frequency of resonating member 102. This change in resonant frequency may be detected to indicate that a positional displacement has occurred.
In another example, a clocking device may be fabricated from a MEMS resonator. For a reliable clocking device, however, very little to no change of the vibrational frequency of the MEMS resonator may be acceptable. This can prove difficult because many MEMS resonators undergo undesirable frequency fluctuations in response to environmental changes. Thus, a MEMS structure having a compensated resonating member is described herein.